The present disclosure generally relates to a lancing device for generating a puncture wound in a body part of a human or animal to obtain a body fluid sample and, in particular, relates to a lancing device for generating a puncture wound in a body part of a human or animal to obtain a body fluid sample with a first analytical consumable which comprises a lancing element for carrying out an analysis of a medically significant component of the sample with a second analytical consumable which comprises a test element for analytical or diagnostic purposes on the basis of a medically significant component of the sample.
Traditionally, the body fluid sample that is collected, is usually blood. However, in some cases, a interstitial fluid sample may also be obtained. In the following, reference is made to blood as an example of a body fluid without limiting the generality and also as an example for other body fluids that can be obtained from a puncture wound.
Lancing systems usually are comprised of lancing elements, that are typically disposable and intended for single use for piercing into the skin, and a lancing device with a lancing element drive for the lancing movement of the lancing element. The lancing device of such a lancing system has a pressing member for pressing onto the body part in which it is intended to generate a puncture wound and a trigger that enables a user to actuate a puncture movement of a lancing element. Alternatively, the puncture movement can also be triggered automatically by pressing the lancing device onto the skin. The lancing element can be, for example, a lancet, a needle or a needle element. Such lancing elements can, for example, be inserted into a lancing device in a magazine.
Disposable lancing elements have been used for a long time to take a small amount of blood from a body part, usually from a finger or earlobe, for analytical-diagnostic purposes. In one embodiment, the lancing elements are usually referred to as lancets. Lancets, intended for manual puncture, are usually used only by medically trained personnel. Nevertheless, the puncture can be associated with considerable pain.
Lancing devices which contain a lancing element drive have also been used for a long time. It is often necessary to regularly monitor certain analytical values of the blood. Lancing devices can be used in particular by diabetics who have to check their blood sugar level several times daily by means of a blood sugar self-monitoring, in order to maintain their blood sugar Additionally, checking blood coagulation parameters by patient blood coagulation self-monitoring is also widespread. The lancing device can be disposable, i.e. only intended for single, with a permanently integrated lancet. However, as a rule, it can be used many times and has a holder in which one lancet at a time can be coupled interchangeably with the lancing drive. Since the devices and lancets are elements that arc adapted to one another and supplied by the same manufacturer, they are referred to as a “lancing system” or “blood collection system.”
A spring, or an electromagnetic drive, is usually used as a drive element for the lancet drive arranged in a housing of the lancing device. A lancet guide ensures that the lancing movement takes place on a predetermined puncture path. In this process, the movement of the lancet towards the skin surface until the reversal point (i.e., propulsion phase of the lancing movement) is driven for example by a spring system, or an electromagnetic drive, and a corresponding drive can be provided for the return movement of the lancet (i.e., return phase of the lancing movement).
Typically, lancing devices have an exit opening from which the tip of the lancet emerges for a short time to generate a wound in a body part against which the lancing device is pressed. The lancing depth is defined by the distance in the puncture direction between the position which the lancet tip reaches at the reversal point of the lancet movement and the plane of a skin contact face which surrounds the exit opening in a ring shape and rests against the skin at the moment of puncture. Hence, the lancing device with the skin contact face forms a lancing depth reference element which ensures that the lancing depth corresponds to a specified value.
In order to control the lancing depth, it is customary to limit the path of travel of the lancet in the puncture direction, for example, by a stop member connected to the lancet which strikes a corresponding stop face in the housing of the lancing device.
Such blood collection systems have to fulfill high demands when it is necessary to regularly monitor certain analytical values of the blood. This applies particularly to diabetics which should frequently check their blood sugar level in order to maintain their blood sugar level within certain target limits by adapting insulin injections to the requirements (which varies greatly depending on the food intake, physical activity etc.). Extensive scientific investigations have proven that an intensive care with at least four blood analyses per day can dramatically cutback severe late sequelae of diabetes mellitus (for example, a retinopathy with resulting blindness of the patient). A prerequisite for this intensive care is that the frequent blood collection is associated with the lowest possible pain.
Consequently, an aim in the development of lancing systems is to generate a puncture wound with as little pain as possible from which a usable sample, i.e. an adequate amount of a body fluid can be collected. The puncture depth is of major importance for the pain sensation as well as for the sample collection. In general, the pain sensation increases with an increasing puncture depth as does the amount of liquid which can be obtained from the puncture wound. Hence, a requirement for lancing devices is only to take a small amount of a blood sample which is sufficient for carrying out the analysis and to arrange for a puncture depth which, on the one hand, is as small as possible and, on the other hand, is as deep as necessary; and there are various developments for making the blood collection as pain-free as possible.
In practice, a blood collection system is, however, not only expected to meet the requirements for a minimal pain sensation but at the same time it should be simple to operate, have a compact slim design and enable a simple, cost-effective construction. On the basis of these practical requirements, blood analysis devices have been and are being developed which satisfy these in some case contrary requirements to as large an extent as possible.
Since the puncture depth should be set to a smallest possible value, it may be the case in practice that no blood sample or an inadequate blood sample is obtained by a puncture. Therefore, endeavors have been made in the prior art to reduce the risk of an unsuccessful puncture. For example, lancing devices with a pressure sensor are known in which a puncture movement is automatically triggered as soon as a pressure presses on the pressing member which exceeds a predetermined minimum pressure.
Whereas in hospitals and doctor's offices several milliliters of blood of a person to be examined are often collected by venepuncture for the analysis in order to thus allow a plurality of laboratory tests to be carried out, nowadays a few μl blood is often sufficient for individual analyses which are directed specifically to one parameter. The collection of small amounts of sample in the range of a few μl or less for determining analytical parameters is especially widespread for the measurement of the blood sugar level but is also for example used for determining coagulation parameters, triglycerides, HBA1c or lactate.
Such small amounts of blood do not require a venepuncture but can be obtained with the aid of a sterile, sharp lancet which is thrust through the skin, e.g. into the finger pad or the earlobe of the person to be examined. This method is especially suitable when the blood sample can be analyzed directly after the blood collection.
The lancets used to obtain body fluid from a body part by generating a small puncture wound usually have a metal lancet needle the tip of which can be sharpened. These lancets must be stored sterilely until use and should be preferably disposed of after use in such a manner that they cannot result in injury. Hence, blood collection systems have been proposed in which the lancets are stored in a lancet storage container in which a plurality of lancets are kept in store for removal from the lancet storage container at a removal position.
A possible embodiment of such a lancet storage container is a drum magazine from which the lancets can be individually removed wherein the lancets are disposed in chambers in the drum magazine which are each individually closed. The used lancets are either disposed of outside the device or outside the analysis device or they can also be returned to the lancet storage container after use for safe disposal.
A blood glucose measuring instrument is a measuring instrument with the aid of which it is possible to qualitatively or quantitatively determine the blood sugar content. Usually for this purpose a puncture wound is generated in a body, a drop of blood is taken, the drop of blood is applied to the test element and the blood glucose content in the drop is determined with the aid of the test element and blood glucose measuring instrument.
Such analysis devices comprise an instrument housing, a measuring device disposed in the instrument housing for carrying out the analysis on a sample obtained with the lancing device and a processor with a software for processing the measured values determined by the measuring device and for processing the analytical measuring data from the measured values which usually takes into account calibration values.
Test procedures which use test elements are widely used for the qualitative and quantitative analysis of components of a liquid sample, in particular, a body fluid of humans or animals. The test elements contain reagents. The test element is brought into contact with the sample for carrying out a reaction. The reaction of sample and reagent leads to a change of the test element which is characteristic for the analysis and is evaluated with the aid of a suitable analysis device. The analysis device is usually suitable for evaluating a very special type of test element of a particular manufacturer. The test elements and the analysis device form mutually matching components and are referred to overall as an analysis system.
Numerous different types of test elements are known which differ in their measuring principle, the reagents used and in their construction. The use of magazines for test elements and/or lancing elements is known in this connection.
With regard to the measuring principle, colorimetric analysis systems are particularly widespread. In these systems, the reaction of the sample with the reagents contained in the test element results in a color change which can be measured visually or by means of a photometric measuring device. In addition, electrochemical analysis systems have become very important where the reaction of the sample with the reagents of the test element results in an electrically measurable change (of an electrical voltage or an electrical current) which can be measured with appropriate measuring electronics. Such analysis systems are also referred to as amperometric systems.
With regard to the configuration of test elements, strip-shaped test elements (so-called test strips) are common and essentially consist of an elongate support layer made of plastic material and test fields mounted thereon. The test fields usually consist of one or more test layers containing reagents. Such test strips are widely used especially for blood and urine analyses.
In a second type of test element, a test field is surrounded by a frame similar to a photographic slide. The test field of this type of test element usually consists of one or more test layers which are held by the frame and contain suitable reagents for colorimetric tests. After applying the sample to the test field and after the test reaction is completed, the color formation can be observed or measured photometrically.
Lancets and suitable devices for them, i.e. so-called “lancing aids,” which enable blood to be collected in a manner which is as free of pain and reproducible as possible are available especially in the field of so-called “home-monitoring”, i.e. where medical laymen themselves carry out simple analyses of blood and, in this case, especially for the regular blood collection by diabetics that has to be carried out several times daily to check the blood glucose concentration, and, in this case, it is important that it should be possible to simply and reliably operate the blood glucose measuring instrument, and the determination and display of the measurement results should be informative and reliable.
The common analysis devices are so-called stand-alone measuring instruments. These instruments work autonomously, singly and independently. They, therefore, have a display, a measuring device, a power supply and a complete user interface which can for example comprise a keyboard, a display, a signal generator or a user guidance. The intended use and properties of such instruments are defined apart from a few adaptations of the firmware.
A known instrument concept for blood analysis devices is based on the use of “integrated disposables” which are an integrated combination of in each case an analytical consumable (disposable) in the form of a lancing element (needle element for carrying out the puncture) and an analytical consumable (disposable) in the form of a test element (e.g., test chemistry for carrying out the analysis or diagnosis). A lancing element which is integrated into the test element is available or provided for each test element. Thus, in an integrated disposable the first and the second analytical consumable are integrated into an analytical consumable which comprises a lancing element for carrying out the puncture process for collecting the sample of a body fluid as well as a test element for carrying out the analysis of a medically significant component of the sample. Depending on the focus one also refers to a lancing element with an integrated test element or a test element with an integrated lancing element.
The transfer of the blood drop obtained by the lancing element to an analysis sensor or test element is carried out with the aid of a capillary channel which runs in the instrument housing. This is an example of a lancing system whose needle element has a capillary channel through which a body fluid can be transported from the skin into the interior of the lancing unit.
Another example of such a lancing system is described in the U.S. Patent Application US 2003/0018282 A1. Here the lancing unit does not only comprise the needle inserted into the skin with a capillary channel suitable for transporting the sample, but also a detection area containing reagents. Such a lancing unit which simultaneously contains a receiving area for the sample (for example, in the form of a capillary-active suction layer and/or hollow chamber) and preferably also the reagents required for the analysis. These lancing system is also referred to as a “microsampler”. With regard to further details on microsamplers reference is made to the above-mentioned U.S. Patent Application and the documents cited therein, in particular the U.S. Pat. No. 5,801,057. Apart from the special features described here, microsamplers of different constructions can be used within the scope of the present disclosure.
Integrated disposables can also be used. Integrated disposables are consumables that comprise a lancing element for carrying out the puncture for obtaining a sample of body fluid, for example, a blood sample, as well as a test element, e.g., a test chemistry for carrying out the analysis of a medically significant component of the sample. Such disposables are often used in suitable magazines which for example are in the form of a strip.
There are a number of integrated tests for blood analysis in the patent literature. However, they tend to only describe the test construction (U.S. Pat. No. 6,607,658 and EP 1402812 A1 as examples of test elements with an integrated lancet or US 2002/0168290 A1 as an example of a sampler with an integrated test chemistry or an integrated sensor). Some publications deal with drives for the lancing element which extend from simple ballistic spring mechanisms (US 2006/0178600 A1) to an electrical direct drive. Furthermore some publications also concern methods which assist the escape of blood by certain movement profiles (e.g. U.S. Pat. No. 7,025,774).
Integrated disposables are for example also described in the documents U.S. Pat. No. 6,607,658 or US 2002/0168290 A1. After a puncture process by a needle element, a sample is subsequently automatically taken up which can take place either directly by the test element, see e.g. U.S. Pat. No. 6,607,658 or by means of a capillary structure of the needle in which case the blood is subsequently guided to the test field. U.S. Pat. No. 7,025,774 for example describes an integrated system with appropriate drive units.
In everyday life, it is not uncommon that after a puncture of the skin, no sample can be obtained, or only an inadequate sample is obtained, be it due to faulty handling or be it due to the fact that the correct depth setting for the puncture had not yet been determined.
However, before the blood can be taken up by the disposable, blood must previously have been automatically expressed which usually takes place by means of a so-called finger cone or ring which exerts the appropriate pressure on the fingertip such that the blood expression step is assisted. Thus, blood can already be collected during the lancing process, e.g., by means of the needle element below the skin or subsequently be collected from the skin surface. In practice, it turns out that the success of the blood expression step and of the blood collection often depends on many other factors (elasticity of the skin, skin temperature etc.) so that the current “success rate” of the expression and blood collection process is not 100%. Since the disposables are usually only intended for single use, the disposable is thus discarded without being used when the collection process is unsuccessful.
Such integrated, or highly integrated, measuring instruments, especially those for mobile use such as home-monitoring, pose various problems: (1) A fresh lancet is used for each blood withdrawal resulting in a lancet magazine that requires more volume in the blood analysis device than the magazine for the test elements. Therefore, in order to reduce the size of the blood analysis device it is desirable to reduce the volume of the lancet storage container, (2) It is assumed that the integrated disposable, i.e. the combined lancing and test element is intended for single use and is discarded after a cycle of use is completed. An unused test is then also discarded when the blood collection did not function. A new disposable has to be used for a new attempt, and (3) For a user of integrated disposables it is very important that the sample analysis is carried out with a very high success rate so that no disposables are wasted due to the costs of these consumables which are higher than those of simple lancing elements or test elements. It is a goal to have a success rate considerably more than 90% and, in practice, almost 100% in order that such a system is accepted by the users. The users to an increasing extent bear the costs for the consumables themselves. According to the prior art, a high degree of technical complexity is necessary to achieve a high success rate.
An analysis device with an integrated lancing device is known from WO 2005/104949 A1 in which a control device checks whether the sample discharged at the puncture site after the puncture with the lancing element is sufficient for carrying out an analysis with a test element. The use of integrated analysis elements comprising a lancing and test element is proposed. If the amount of sample accumulated at the surface of the skin in a puncture process is insufficient to carry out an analysis, this can be reported to the user by means of a signal device. As a result the device is again placed over the puncture wound and a second puncture process is carried out with the same or with another lancing element. An additional quantity of sample can be obtained by an expression device of the instrument which is used to squeeze the puncture site. If the device has been accidently removed from the puncture site after the first puncture process, it is also possible according to this document for the user to manually squeeze the skin in order to obtain fluid and to again place the device over the puncture site in order to thus take up and analyze the sample. The document only describes cases in which an additional puncture takes place automatically if an inadequate amount of sample was obtained. In general once an inadequate amount of sample is detected the procedure is according to the principle: more of the same, i.e. more punctures, greater lancing depth, more milking effort etc., but always while basically retaining the process typical for the device as in the first attempt at sample collection.
A comparable analysis device is proposed in US 2003/0208140 A1. In this case, it is checked whether an adequate amount of sample has been obtained. However, nothing is said on how to proceed when inadequate amount of sample to carry out an analysis is found.
Therefore, there is a need to provide a lancing device or an analysis device with a very high success rate in the collection of a sample of a body fluid which is obtained in a technically uncomplicated manner, especially using integrated disposables.